It is known that the heat-transfer printing method consists of bringing into contact one side of the textile material and one side of an inert support for carrying dyes which can be sublimed, then of causing the sublimation of the dyes and their transfer from the support to the textile material, then finally of separating the textile material from the support.
The invention relates more particularly to the continuous treatment of a textile material of great length, where one brings about joint longitudinal travel of the textile material and of the dye carrier, which is also provided in a great length. The sublimation of the dyes and their transfer are ensured by a device such as a heated roller located in the usual path of the material to be dyed and of the dye carrier and bringing about continuous transfer.
This method is widely known and is completely satisfactory both when dying synthetic fibres as well as when dying natural fibres, on condition that certain modifications are made to its method of implementation and in the nature of the dyes used.
However, difficulties are encountered in carrying out this method as soon as one wishes to apply the latter to textile materials which are wider than the standard width of commercially available inert carrier belts for the dyes. This is the case for example when one wishes to print by the heat-transfer method, materials such as carpets, wall paper, cloth, wall coverings or floor coverings having a width of 4 or 5 meters for example, using inert carrier belts for dyes having a standard width of 1.60 meters.
In this case, certain users have taken measures to supply the device carrying out the heat-transfer printing proper and for example the heated roller simultaneously with a plurality of longitudinal belts carrying dyes, which are unwound side-by-side.
This method may be satisfactory when it is not absolutely necessary for the motifs printed by the various adjacent belts to join exactly, i.e. as long as one is not printing a motif whose coloured parts must have a continuous appearance over the width of the textile material. This is so for example when printing a motif formed by a bed of flowers on a light background or by garlands arranged over the length of the material.
On the other hand, when the coloured parts of the motifs must join laterally and for example when printing a motif whose background is coloured or a motif having garlands arranged over the width of the textile material, this method is not satisfactory owing to the unaesthetic appearance caused by an even slight displacement between the various belts of the inert carrier for the dyes.
In fact, if it is within the ability of a man skilled in the art to adjust the displacement of the various adjacent belts such that the motifs defined by the dyes which can be sublimed are in an identical longitudinal position when brought into contact with the textile material for the purpose of heat-transfer printing, perfect transverse juxtaposition of the various belts as they travel is particularly difficult to achieve.
One finds either a transverse separation of the belts with the appearance of longitudinal "blanks" on the material printed by the heat-transfer method, or on the contrary mutual overlapping of adjacent belts, with the appearance on the printed material of darker longitudinal strips owing to the excess amount of dye in the overlapping region, adjoining longitudinal lines where the motif has a blurred appearance, the dyes carried by the edge of one belt from which the textile material is separated by the edge of another belt tending to spread laterally.